Subway riders are being squashed together on increasingly crowded trains, new data revealed Monday — and lack of basic manners getting in and out of cars is contributing to a spike in delays.

Weekday trains experienced overcrowding delays a staggering 14,843 times in December — the most recent month for which data were available.

That is a 113 percent increase from a year earlier.

“I’ve seen children crushed,” said Bronx rider Ansley Davenport, who added she’s witnessed riders chide parents for bringing kids on the train during rush hour.

She said she regularly has to let two crowded trains pass at the 14th Street station before she can board a train home to Pelham Parkway.

“My commute to work is consistently a half-hour or even longer than necessary, because they refuse to run enough [No.] 2 trains at rush hour. My train uptown home often takes 15 minutes or more to arrive at rush hour. When it does, it’s often too crowded to get on.”

And the problem isn’t just during workdays.

Weekend trains were delayed in reaching the end of the line 2,314 times because of overcrowding in December, a 146 percent spike from 941 during that month in 2013.

The delays have gone up as record numbers of riders pack trains to the gills.

Six million people crammed into subway cars on 29 different days in 2014 — the most since the MTA started tracking ridership.

To make riders’ commutes more bearable, the MTA launched a courtesy campaign early this year to curb vile behaviors such as manspreading — when men take up an extra seat with their open legs.

The ads also target New Yorkers who board a train without letting riders who are getting off exit.

The MTA is upgrading the signal system on lines such as the 7, which will allow it to run more trains.

Officials said the subway system is still experiencing overall delays because of Superstorm Sandy damage and maintenance work that’s part of the capital plan.

The MTA has been using the FASTRACK program to more efficiently do maintenance work in which significant parts of a line are shut down for several nights.

A new electronic train tracking system called I-TRAC was recently introduced on letter lines to better catch delays.

The MTA’s operation planning team also has been adjusting running times to try to make service more reliable, and trains more evenly spaced.

It uses real-time tools in its rail control center to track service and closely monitor what’s going on underground.